func main() {
err := initGL()
if err != nil {
log.Printf("InitGL: %v", err)
return
}
defer glfw.Terminate()
// Create our texture atlas.
atlas := glh.NewTextureAtlas(AtlasSize, AtlasSize, 4)
defer atlas.Release()
// Fill the altas with image data.
fillAtlas(atlas)
// Display the atlas texture on a quad, so we can see
// what it looks like.
for glfw.WindowParam(glfw.Opened) > 0 {
gl.Clear(gl.COLOR_BUFFER_BIT)
// Bind the atlas texture and render a quad with it.
atlas.Bind(gl.TEXTURE_2D)
gl.Begin(gl.QUADS)
gl.TexCoord2f(0, 0)
gl.Vertex2f(0, 0)
gl.TexCoord2f(1, 0)
gl.Vertex2f(AtlasSize, 0)
gl.TexCoord2f(1, 1)
gl.Vertex2f(AtlasSize, AtlasSize)
gl.TexCoord2f(0, 1)
gl.Vertex2f(0, AtlasSize)
gl.End()
atlas.Unbind(gl.TEXTURE_2D)
glfw.SwapBuffers()
}
}
// createAtlas loads the current LEM1802 font into a texture atlas.
func (d *LEM1802Display) createAtlas(gw, gh int) {
if d.atlas == nil {
d.atlas = glh.NewTextureAtlas(gw*32, gh*6, 1)
}
if d.glyphs == nil {
d.glyphs = make([][4]float32, 128)
}
atlasWidth := float32(d.atlas.Width())
atlasHeight := float32(d.atlas.Height())
img := image.NewAlpha(image.Rect(0, 0, gw, gh))
font := d.dev.Font()
pw := uint(gw / 4)
ph := uint(gh / 8)
d.atlas.Clear()
for i := 0; i < 128; i++ {
a, b := font[i*2], font[i*2+1]
region, ok := d.atlas.Allocate(gw, gh)
if !ok {
continue
}
d.glyphs[i][0] = float32(region.X) / atlasWidth
d.glyphs[i][1] = float32(region.Y) / atlasHeight
d.glyphs[i][2] = float32(region.X+region.W) / atlasWidth
d.glyphs[i][3] = float32(region.Y+region.H) / atlasHeight
drawGlyph(img, pw, ph, byte(a>>8), byte(a), byte(b>>8), byte(b))
d.atlas.Set(region, img.Pix, gw)
}
d.atlas.Commit(gl.TEXTURE_2D)
}